ZFS storage's snapshot size checking method

Dear All.

My CU using ZFS7420 Storage for their exadata db backup and I want to know the snapshot size exactly.

I used to check available pool size and snapshot size via below method.

They taken snapshot daily after db backup automatically, project base snapshot taken(Not per volumes)

1. Shares -> Projects Usages on ZFS WEB GUI.

I Can show the bleow informaion on Usages tab.

Usage  60% of 25TB

Referenced data        10T

Snapshot data           5T

Total space                15T

df -h command display that on nfs mounted host was not strange.

Available size is 10TB remains.

2. My quesiton is in Project's snapshot list pages.(Shares ->  Projects -> Snapshots)